The present invention is an improved design of the ducted fan set forth in U.S. Pat. Nos. 2,554,602, 2,554,600 and 2,554,601.
The general concept of providing ducted fans with a multiplicity of concentrically spaced cone-shaped ducts in their intakes to increase the air output of the fan has been well known for many decades as typified in U.S. Pat. Nos. 2,287,822 and 2,330,907. Having a ducted fan with multiple cones co-axially spaced in telescoping relation not only provides an increased output at a given power use but also functions as a safety grill in conjunction with the connecting ribs. The outer cowling also can function as a bumper housing to deflect and absorb energy when the fan falls or impacts a stationary object.
All of the above-mentioned patents illustrate fans which could not be sold today by reason of the large grill openings on the front and back of the fans. Current OSHA requirements require consumer fans to have grills with a maximum lateral opening of one-half inch.
It is therefore the principal object of the present invention to provide a new and improved front grill and duct structure which increases the fan's capacity and efficiency while decreasing its sound over the prior art grills or no grills at all.
Another object of the present invention is to provide a new and improved ducted fan wherein the front grill and the inner cowling are integral and are easily removable by deflecting four separate tabs positioned around the periphery of the outer cowling.
Another object of the invention is to provide a new and improved single leg support for the fan which allows the fan to pivotally turn on the support while a preloaded spring counteracts the offset weight of the fan and retains it in place. The support leg also is a conduit for the wires which supply the motor.
Further advantages and features of the invention are set forth in the following detailed description and accompanying drawings which embody the present invention.